When An Ancestry Test Tells You Your Dad isn't Your Dad

"Sometimes your DNA family can be the greatest gift of all." That's one message that greets visitors to the website for 23andMe, a company that promises to "analyze, compile, and distill" a sample of your DNA in order to help you "understand who you are, where you came from, and your family story."

And there are plenty of uplifting stories to pick from: Take Michael, for instance, who went looking for information about himself after his adoptive parents died. With the help of 23andMe, he found not only his birth father, but nine brothers and sisters as well. Or there's Winnie, also adopted, who always felt something was missing in her life. Genetic testing helped connect her with the family who never knew she existed. Diane's family moved across the country during the Depression when she was a kid. After her mother died, Diane lost touch with her mother's side of the family, and though she later spent decades looking for them, she was never able to track them down. A gene test led Diane to two first cousins and a long-awaited family reunion.

There's no question genetic ancestry tests have opened doors for people. Just spit into a tube and they can show you what parts of the world your ancestors came from, what kind of diseases you might be at risk of developing (or not), and even how much Neanderthal DNA you have. Some of these tests can also help you find relatives, like in the cases above. But while those stories had happy endings, not all of them end with long-lost relatives hugging it out. In many cases where people discover unexpected family—secret adoptions, hidden affairs, past relationships—accidentally uncovering family secrets can have major consequences. Likewise, many people want these companies to start doing more to protect customers from potentially damaging fallout as a result of, well, their results.

Telling his story to Vox under the pseudonym George Doe, one 23andMe user described such an experience. His decision to test himself and his parents began as a demonstration for a class he was teaching on genetics. He figured getting some information on what kind of cancers he might be prone to would be an added bonus. Instead, he ended up finding a half-brother, a son of his father's that his family didn't know about.

George reached out to his newly discovered half-brother, Thomas, and found out he was adopted at birth and had spent years looking for his birth parents. But the news of Thomas wasn't welcome information for the rest of George's family. It unearthed a lot of deep-seated family pain, led to his parents' divorce, and initiated some truly agonizing family upheaval. "I'm really devastated at the outcome," George said, "I still hold out hope that in time we can resolve things. But I also worry that as these transitions happen there may have been some permanent emotional damage that may not be able to be undone."

Thomas showed up as one of George's relatives in the 23andMe database because George had clicked the little box that allows you to see close family relatives that have also used 23andMe—an opt-in option available to 23andMe customers. After George's dad opted in, Thomas showed up as a family member for him as well.

Discoveries like these can have heartbreaking effects, and while they may be hard to prevent, George said he'd at least like to see some sort of statement on the risks of finding out sensitive information. "I would want a warning saying 'Check this box and FYI: People discover their parents aren't their parents, they have siblings they didn't know about. If you check this box, these are the things you'll find,'" he said.

Of all of the genetic ancestry test companies, 23andMe is actually one of the only ones to directly address this possibility. Their website states: "Looking at your genetic data might uncover information that some people find surprising. This information can be relatively benign. At other times, the information you learn can have profound implications for both you and your family." The company even goes on to explicitly remark on surprising family results: "In a similar way, genetic information can also reveal that someone you thought you were related to is not your biological relative. This happens most frequently in the case of paternity, where someone learns that their biological father is not who they thought it was."

This information is put in front of a customer while they navigate the 23andMe tools. "More specific examples of customer messaging happen in real time before a customer experiences new information and tools," says 23andMe privacy officer Kate Black, "For example, we surface information about learning unexpected relationships and require customers to consent prior to participating in our genetic relatives tool."

That kind of warning is something Maarten Larmuseau, a researcher in the Department of Biology at the University of Leuven in Belgium, would like to see other genetic ancestry companies incorporate as well. But Larmuseau also hopes companies will go a step further and make efforts to protect an arguably even more vulnerable group: kids. In a new study published in the European Journal of Human Genetics, Larmuseau and his colleagues looked at the policies of 43 genetic ancestry companies to see what sort of rules they had about the testing of minors. Nearly half had no information at all about the testing of minors and only a quarter explicitly stated that minors had to have the consent of a parent or guardian in order to be tested. Further, only ten companies included statements warning users about the risks of unexpected or sensitive results, three of which specifically mentioned the possibility of finding out your dad isn't your biological father.

"Nobody is seeing these recreational genetics tests as a real problem," Larmuseau says, pointing out that part of the issue is that people usually don't discuss the painful results of genetic ancestry tests because things like false paternity are taboo to talk about openly.

I reached out to a number of the companies analyzed in Larmuseau's study, the vast majority of which didn't have such a warning. EasyDNA, one of the companies without a warning about uncovering sensitive information, replied that the tests "are not designed to establish paternity or maternity, and any inferences a client makes about whether their father is actually their father based upon the results of an ancestry test is something we would strongly discourage. The only conclusive test to know if an alleged father is the biological father of an individual is a paternity DNA test." Another company, UK-based DNA Worldwide, also lacked such a warning on its website. But after Larmuseau's study was completed, DNA Worldwide's ancestry testing services were moved over to Living DNA, which does have a clear section dedicated to the effects of what their tests' findings could have on a consumer. No other companies responded to requests for a comment on their decision to not include a warning.

Regarding minors, 23andMe is again one of the companies with much more transparent language. Their terms of service require you to be at least 18 years old to submit your own saliva sample. "You must be the minor's parent or legal guardian to consent on their behalf," Black says. And a parent or legal guardian also has to consent before 23andMe can use a child's genetic sample for research. EasyDNA has a similar statement in their terms. A representative from the company added, "When testing a minor, we also explicitly make it clear on the submission forms—which clients must return with their samples—and the terms and conditions that we need a legal guardian to consent to the test. Testing is not allowed to proceed if we are not satisfied we have the necessary signatures." (I reached out, again, to the companies that don't have clear language regarding minors using their products, which made up nearly half of the companies in Larmuseau's study. None responded to my request.)

In an earlier study, Larmuseau found that cases of misattributed paternity occurred at a rate of around 1 or 2 percent. Obviously, not all of those cases will be found out by a genetic ancestry test, and not every secret adoption or unknown offspring will be uncovered that way, either. But those that are can have lasting consequences on the people involved. "It might have an emotional impact that looks like post-traumatic stress, depression, or anxiety," says Sarah Lowe, an assistant professor of psychology at Montclair State University.

In addition to accidental discoveries, there's also the potential for these types of tests to be purposely used as paternity tests, resulting in the same sort of family tumult as an accidental discovery. This is further complicated in countries like Switzerland or France, where testing for paternity requires maternal consent or a court order, laws for which genetic ancestry tests represent a loophole. To help shelter children from this kind of upheaval and emotional stress, Larmuseau suggests that companies clarify their policies on minors. "The least you can ask is for a clear statement on [whether or not] minors can participate. And maybe if the child is participating, the [parents] should have to give consent," he says, "just as they would for a medical procedure."